Why do I have a P0300 code?

Darla Garrett

Asked by Jul 08, 2015 at 08:36 AM about the 2001 Chevrolet Blazer 4 Door LS

Question type: Maintenance & Repair

New engine installed last week. This is the second new engine in 18 months. The first one failed and thankfully was under warrenty. I picked it up Thursday and it runs better than it has in years. Problem is, I have a SES light on. The codes were P0300 random misfire and P0135 O2 sensor. We changed the O2 sensor and took it back to the shop for the P0300. They can not find the problem. The latest is they want to pull the engine away from the torque converter/transmission to see if they are bad and throwing the engine off balance. Can that be possible?

4 Answers

Tim Klingenberger

Have they changed the spark plugs or checked the ignition coils? This is most often the cause of misfire besides bad computer signal.

Darla Garrett

They put new plugs and wires. I don't think they checked much of anything. My main question is can the torque converter/transmission cause a false P0300 code? I think they are tired of working on my vehicle since most of the work has been warrenty work and they are not really making any money.


Did they check for proper fuel pressure. I would also have them look at the crank and camshaft sensor to see if they are aligned correctly.

Michael Miller

The multi misfire can also happen if you have clogged injectors. Happened to me and I ran some fuel injector cleaner through and it took care of the issue. Hope this helps.

Your Answer

Add photo

Related Questions


Looking for a Used Blazer in your area?

CarGurus has 1,634 nationwide Blazer listings starting at $1,999.


Search Chevrolet Blazer Questions

Chevrolet Blazer Experts

#1 Andrew Olsen
Andrew Olsen
Reputation 1,690
#2 yetilikesbeer
Reputation 1,010
#3 dandyoun
Reputation 630
View All

Related Models For Sale

Used Chevrolet TrailBlazer"
136 Great Deals out of 6,221 listings starting at $999
Used Chevrolet Tahoe"
1,160 Great Deals out of 36,620 listings starting at $1,995
Used Chevrolet S-10"
9 Great Deals out of 1,809 listings starting at $1,749
Used GMC Jimmy"
373 listings starting at $1,900
Used Chevrolet Silverado 1500"
2,496 Great Deals out of 144,768 listings starting at $1,995
Used Ford Explorer"
1,396 Great Deals out of 72,124 listings starting at $300
Used Jeep Grand Cherokee"
1,231 Great Deals out of 74,214 listings starting at $1,500
Used Jeep Wrangler"
452 Great Deals out of 16,379 listings starting at $2,500
Used Ford F-150"
3,287 Great Deals out of 217,270 listings starting at $1,000
Used Chevrolet Camaro"
840 Great Deals out of 39,078 listings starting at $2,650
Used Chevrolet Impala"
987 Great Deals out of 35,893 listings starting at $700
Used Chevrolet Suburban"
677 Great Deals out of 24,305 listings starting at $1,985